Research on a novel liquid-solid phase change self-supporting fracturing fluid system

Hydraulic fracturing technology is widely used in the stimulation of oil reservoirs. However, the insufficiently broken of high-viscosity polymer that only serves the purpose of carrying proppant , which not only damages the permeability of fractures, but also causes a large amount of resource waste. Meanwhile, the high-density proppant is difficult to support micro-fractures, reducing oil and gas recovery. In response to these issues, this study designed a skeleton monomer SEC 3 R with a viscosity of 0.62 Pa s as the active monomer, and through the selection of crosslinking agents and initiators, a liquid-solid phase change self-supporting fracturing fluid was developed. It was found that when the volume ratio of phase change liquid and non-phase change liquid was 1:2, the total proportion of proppant in 20–40 mesh and 40–70 mesh was the highest, which was 96.64%. Compared to quartz sand and ceramsite proppants, liquid-solid phase change proppants have a more regular sphericity and smoother surface, which gives it better conductivity. The conductivity of liquid-solid phase change proppants with 20–40 mesh and 40–70 mesh under a closure pressure of 10 MPa was 123.50 and 39.89 μm 2  cm, respectively, and under a closure pressure of 40 MPa, the conductivity was 15.86 and 9.62 μm 2  cm, respectively. Its long-term conductivity was better than that of quartz sand proppant and similar to that of ceramsite proppant.